cpu/native/periph/timer: fix undefined behaviour
cpu/native/periph/timer: fix undefined behaviour

OlegHahm/RIOT,miri64/RIOT,kaspar030/RIOT,jasonatran/RIOT,kYc0o/RIOT,miri64/RIOT,ant9000/RIOT,jasonatran/RIOT,smlng/RIOT,yogo1212/RIOT,kaspar030/RIOT,kaspar030/RIOT,rfuentess/RIOT,RIOT-OS/RIOT,toonst/RIOT,toonst/RIOT,ant9000/RIOT,yogo1212/RIOT,lazytech-org/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,BytesGalore/RIOT,OTAkeys/RIOT,kYc0o/RIOT,rfuentess/RIOT,yogo1212/RIOT,yogo1212/RIOT,mfrey/RIOT,lazytech-org/RIOT,mfrey/RIOT,x3ro/RIOT,x3ro/RIOT,jasonatran/RIOT,toonst/RIOT,A-Paul/RIOT,x3ro/RIOT,authmillenon/RIOT,lazytech-org/RIOT,BytesGalore/RIOT,RIOT-OS/RIOT,lazytech-org/RIOT,basilfx/RIOT,toonst/RIOT,mfrey/RIOT,basilfx/RIOT,toonst/RIOT,josephnoir/RIOT,mtausig/RIOT,OTAkeys/RIOT,cladmi/RIOT,kYc0o/RIOT,A-Paul/RIOT,OTAkeys/RIOT,authmillenon/RIOT,cladmi/RIOT,A-Paul/RIOT,authmillenon/RIOT,basilfx/RIOT,ant9000/RIOT,x3ro/RIOT,mfrey/RIOT,jasonatran/RIOT,ant9000/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,smlng/RIOT,josephnoir/RIOT,cladmi/RIOT,mtausig/RIOT,cladmi/RIOT,A-Paul/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,kYc0o/RIOT,cladmi/RIOT,aeneby/RIOT,rfuentess/RIOT,aeneby/RIOT,OlegHahm/RIOT,authmillenon/RIOT,OTAkeys/RIOT,ant9000/RIOT,kaspar030/RIOT,josephnoir/RIOT,smlng/RIOT,mtausig/RIOT,BytesGalore/RIOT,josephnoir/RIOT,authmillenon/RIOT,basilfx/RIOT,rfuentess/RIOT,x3ro/RIOT,BytesGalore/RIOT,A-Paul/RIOT,smlng/RIOT,RIOT-OS/RIOT,rfuentess/RIOT,miri64/RIOT,aeneby/RIOT,mtausig/RIOT,mfrey/RIOT,miri64/RIOT,miri64/RIOT,aeneby/RIOT,yogo1212/RIOT,OlegHahm/RIOT,yogo1212/RIOT,lazytech-org/RIOT,basilfx/RIOT,smlng/RIOT,BytesGalore/RIOT,kaspar030/RIOT,mtausig/RIOT,aeneby/RIOT,OlegHahm/RIOT,josephnoir/RIOT,authmillenon/RIOT